[TowerTalk] upper/lower/both box

[N7KA at comcast.net]

Yagi Antenna Design by W2PV, page6-3. 



Arne N7KA 


----- "Jim Thomson" <jim.thom at telus.net> wrote: 
> does anybody remember how these box's were configured ? 
> Buried some where in mu old W2PV material... there is a diagram of one. 
> Think it used a pair of P+B DPDT relays.    This is for 2 x identical 
> 40m yagi's... that's it.  It only has to be configured for one band. 
> Last time round... I designed a simple LC box for a buddy who has 2 x 40m yagi's.   
> The 2 x ant's  were always drioven in phase.  The LC box was simple.. just a mess 
> of shunt NPO 5 kv doorkno caps at left end. [ hot to grnd]   followed by  a series 
> cu tubing coil.    50 ohms in... and 25 ohms out.  The 25 ohms consisted  2 x  coax 
> connectors.. wired in parallel.    2 x identical length 50 ohm cables... one per yagi. 
> I was going to suggest adding bip/bop capability... since that only involves adding 
> 1 x spst vac relay.. and one  x  1/2 wave of coax. 
> IMO... I think BIP /BOP would be plenty.    However.. there maywell be cases where the top 
> ant by itself would be louder than both in phase..... and ditto with bottom yagi [vs BOP] 
> Is the U/L/B box in one of the books ?   If it is..it's  buried good.  This is just for one band... no 
> broadband xfmr's required. 
> Tnx........ Jim  VE7RF   
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